CATALYST ASSESSMENT

DCL carefully considers all mechanisms involved in catalyst deterioration, to ensure the long-term performance of target emissions. DCL maintains a large database of model gas, test cell, and in-field catalyst aging data.

IDEAL SURFACE

  • Good adhesion
  • Well-dispersed particles
  • Similar thermal expansion coefficients of substrate and washcoat

CHEMICAL DETERIORATION

  • Poisoning; irreversible adsorption or reaction on/with the surface
  • Inhibition; competitive reversible
  • adsorption of the poison precursors

> Sulphur poisoning reversible at greater than 600oC / 1110oF, caused by ZDDP (zinc dialkyl dithio phosphate)

> Lube oil poisoning by phosphorus additives (irreversible)

THERMAL DETERIORATION

  • Sintering (re-dispersion)
  • Alloying
  • Support changes
  • Noble metal-base metal interactions

> High-temperature sintering

> Complete collapse of washcoat

> Loss of surface area from 200m2/g to 5m2/g at 1200oC/2200oF

FOULING

  • Carbonaceous deposits (coking)

> Soot and ash deposits, reversible by catalyst washing/cleaning

MECHANICAL DETERIORATION

  • Thermal shock
  • Attrition/erosion
  • Physical breakage